A traditional way of designing and implementing various data processing devices has been based on a centralised application engine. That is, a data processing device typically comprises a central processing unit (CPU), which may consist of one or more processors, and other parts and subunits of the computing system, like the memories, display adapters, I/O adapters, mass storages, graphics accelerators, etc., which are connected to the CPU via one or more system buses. The CPU then controls the operation of the whole computing system by delivering operation command to the subunits and by processing and transferring data to and from the subunits.
However, data processing devices, especially portable devices, like mobile terminals and PDA devices, are becoming increasingly complex, thanks to their colour screens, on-board digital cameras, high-speed microprocessors, etc. Therefore, it seems evident that future device platform architectures will be based on an interconnect centric approach where multiple intelligent sub-systems communicate directly with each other, and not through central application engine as today. For that purpose, many device manufacturers and subunit vendors have started co-operation to develop interconnect centric platform, wherein the interfaces between the subunits are standardized to the necessary extent such that the various subunits from different vendors can automatically communicate with each other. One such co-operation project is known as MIPI (Mobile Industry Processor Interface) Alliance.
Even though the interfaces between the subunits are quite strictly defined and standardized, the subunits and sub-systems, as such, can internally use any technologies favoured by the requirements and competences. Accordingly, the device manufacturer who assembles the final product from a plurality of interconnecting subunits and sub-systems, does not necessarily have any knowledge about the internal implementation of the subunits. Consequently, this black-box approach causes new security threats to the device.
It is possible that one or more sub-systems start malfunctioning due to an error (bug) in the software or hardware implementation, due to accidental or deliberate misuse, or due to deliberate hostile attack resulting from downloaded Trojan virus, for example. A faulty sub-system may, for example, flood power or signals to the interconnect system thereby disturbing other sub-system communication and wasting energy or causing high peak powers possibly leading to shutting down the device. A faulty sub-system may also misuse services and cause financial losses to an end-user, as well as steal end-user's confidential information.
Apparently, there is a need for an arrangement for handling a malfunctioning sub-system in an interconnecting system architecture.